Detection of prostate specific antigen in pancreas and salivary glands: a potential impact on prostate cancer overestimation

PURPOSE: We explored the immunohistochemical expression of prostate specific antigen (PSA) in pancreas and salivary glands. MATERIALS AND METHODS: We investigated 62 specimens from male and female subjects, representing normal cases and several pathological conditions of pancreas and salivary glands. Two commercially available monoclonal antisera for PSA and 1 for prostatic acid phosphatase were used. RESULTS: A consistently positive reaction for PSA and prostatic acid phosphatase, independent of patient sex, was noted in ductal cells of normal pancreas and normal salivary glands, as well as pleomorphic adenoma, adenocarcinoma and all oncocytic epithelial cells of Warthin's tumor. Reaction was absent in normal stromal and acinar cells, and squamous carcinoma. CONCLUSIONS: PSA is detectable in normal and cancer tissues far from the prostate. Therefore, we may not entirely rely on specificity of PSA alone to diagnose metastatic prostate cancer.